Sometimes they never know someone else was there either.
My regular in town has an efficiency and he used to allow one of his friends to use it, he would go run an errand and wait downstairs till his friend was done.
The guys who ran a local agency called DC Boys had a 2 bedroom apartment in an old art deco building, they allowed their escorts to use with a client for 1 or even 2 hours. In the meantime, they would go downstairs to read a book, this was obviously before the iPhone.
@BaronArtz next time the roomie should go downstairs, to a park, a Starbucks, walk around the city, etc.